X-ray apparatus.



E. W. CALDWELL. X-RAY APPARATUS.

1,217,148 AFPUCATION FILED IULY I5; 1911. Patented feb- 27 2 SHEETS-SHEET l- H WITNESSES- E. w. CALDWELL.

X-RAY APPARATUS. APPLICATION FILED lULY 15. IQH.

Pmntea Feb. 27,1917.

2 SHETS-SHEET 2.

WITNES8E8 W EUGENE w. CALDWELL, or NEW Yoiiiihu. Y.

X-RAY APPARATUS.

Application fi led July 15, 1911.

To all whom it may concern:

Be it known that I, EUGENE W. CALD- WELL, a citizen of the United States, and State of resident of the city,

ew York, ful Inventions ratus, of which county, and

have made certain new and use- Relating to X-Ray Appathe following is a specification, taken in connection with the accom-' panying drawings, which form part of the same.

This invention relates especially to X-ray apparatus and may comprise polyphase high potential transformers which may have their primaries simultaneously connected ,to a polyphase supply circuit by an operating switch, there being a working circuit which may comprise an X-ray or other lighting tube, a series of Villard type valve tubes connecting each of said transformer secondaries to each side of said working circuit to deliver superimposed rectified current impulses thereto and operate said tube by substantially uniform direct current. The working circuit may if desired comprise a starting and equalizing coil tending to equalize the normal working current passing therethrough and provided with a mag- .netic core and a starting circuit which is preferably arranged to operate said starting coil and comprising a startingprimary cooperating with its core to energize the same, a source of potential and a magnetic break operated by said core and contacts preferably connected to said operating switch to send intermittent high potential impulses through the working circuit until the normal working current is established therethrongh, whereupon the working current may automatically hold open the magnetic break and allow the substantially uniform working current to actuate the tube at highest efficiency.

In the accompanying drawings showing in-a somewhat diagrammatic way illustrative embodiments of this invention,'

Figure 1 is a circuit diagram.

Fig. 2 is a circuit diagram showing another arrangement of Villa'rd tube rectifiers in connection with polyphase transformers.

Fig. 3 is a detail showing in elevation a series of valve tubes.

Fig. 1 is a transverse section thereof.

Fig. 5 is an enlarged detail showing the construction of one of these tubes.

Fig. 6 shows a modified form of valve tube.

Specification of Letters Patent.

Patented Feb. 27, 1917. Serial No. 638,628.

Fig. 7 shows still another form of valve tube.

In the illustrative shown in the drawings, the polyphasetransformers may be connected and operated in any desired way tentials of 60,000 or more volts for X-ray tube work. Each of the transformer secondaries may be connected in any desired way with each side of the working circuit in which the X-ray tube or otherhigh potential lighting tube or other device is located,

by means of Villard or similar vacuum yalve tubes. a number of such tubes being preferably used in series in each case so as to form a seriesof valve tubes delivering. superimposed rectified current impulses from each of, the transformer secondaries to the working circuit. In Fig. 1 a three-phase arrangement is shown, ondaries being connected in Y while the transformer primariesmay of course be connected in any desired way with the supply circuit. The three-phase transformers'inay forms of apparatus to produce in their secondar es polyphase alternating currents at pothe transformer seccomprise the transformer secondaries 16, 17, I

18 which may, if desired, be connected in each instance to the transformer primaries 20, 21 and 22 and if desired the transformer secondaries may be connected in Y by the connection 19. The direct current or working circuit may comprise the two sides 5 and 9 each of which may be connected with transformer secondaries through each of the a series of Villard type valye tubes which may comprise any desired number of tubes to secure the desired rectifying actionat the operating voltage. In Fig. 1, only two tubes are diagrammatically shown in each series, the arrows indicating the direction of thecurrent which these valve tubes allow to pass. may. connect the side 5 of the working circuit with the connection 10 of the transformer secondary 16 while the series of tubes 11 similarly connects this transformer secondary with the other side ing circuit. Similar series of valve tubes 11 and 12 connect the wire or connection 26 of the transformer secondary 17 with the two sides of the working circuit and the connector 6 of the transformer secondary 18 is similarly connected with the working circuit by the two series of valve tubes, 7 and 9 of the work- 1 The series of rectifylng tubes 13 8. \Vhen these transformers are operatedthe rectified high potentlal current impulses delivered to the working circuit are superimposed and produce a substantially uniform directcurrent therein which may be used to operate an X-ray tube of any desired construction. such as 42, or any other lighting tube or other high potential device, if' desired. The normal working current may, if desired, be further equalized by the use of a suitable equalizing or inductance coil therein which may be in the form of the coil '43 having a suitable magnetic core 144 cooperating therewith. This high inductance equalizing coil of course tends to pre- Vent any variation in the current passing through the working circuit with which this coil is in series and with such an arrangement a substantially uninterrupted and uniform direct current can be secured as shown by oscillographs.

Such a uniform working current is highly desirable in X-ray work, since after the tube is started by any desired starting device the working current can be maintained constantly at the amount giving the highest tube efliciency with the minimum of unclesirable radiation and other undesirable effects, such as destructive action on the tube itself. Practically speaking, the working current is limited by the amount of current which may be used without destructive or decidedly undesirable action on the tube and by keeping the current constantly at such safe maximum very much greater radiographic effects can be secured than by the use of the ordinary induction coils or me chanically rectified single phase transformers. Another arrangement of polyphase transformers and Villard type rectifying tubes is shown diagrammatically in Fig. 2, in which the two-phase transformer primaries 96 are shown as cooperating with the high potentialisecondaries 95. Both ends of each of these transformer secondaries may be connected with the bridge arrangement of rectifying tubes indicated so as to secure a substantially uniform working current in the working circuit 86, 90. The side 86 of this working circuit may be connected with the two series of valve tubes 91, 92, the ends of which connect with the terminals 87, 187 of the transformer secondary and also with the two cooperating series of valve tubes 93, 94 forming the bridge arrangement indicated and delivering the rectified current impulses along the working circuit connection 88 which leads to a similar bridge arrangement of tubes connected to the secondary of the other transformer. These superimposed direct current impulses in the working circuit are quite uniform and may be still further equalized by the use of suitable equalizing coils or devices as previously described.

The transformers shown in Fig. 1 may be conveniently operated by the arrangement of circuits shown diagrammatically in connection therewith which may comprise a series of contacts 23 connected to different points in each of the transformer primaries so as to put more or less primary turns in circuit and correspondingly regulate the secondary potentials secured. These contacts may cooperate with the simultaneously operated contact arms 25 which may be conveniently mounted on a suitable switch bar 24 so as to be insulated from each other and simultaneously swung into engagement with the contacts 23 when the regulator switch handle 26 connected to the bar is operated. These switch arms may be connected by the wires 30 29 and 31, 27 with the contacts 130, 129 and 127 of the three-pole double throw switch 32. The blades of this switch may as indicated be connected with the switch contacts 115, 126 and 106 which are connected through the wires 15, 26 and6 with the other ends of the transformer primaries. By throwing this switch 32 upward so that its blades engage the contacts 130, 129 and 127 the transformer primaries are connected in delta, while when the switch 32 is swung downward so as to electrically connect all its switch blades by the through connection 33 the transformer primaries are connected in Y. The three-phase supply circuit 37, 40, 39 may be connected with the transformer primaries in any desired way as by the use of the operating switch 36 which when closed electrically connects the supply circuit with the wire 27, 31 and the switch arm 25 cooperating with the transformer primary 20. This operating switch also connects the supply circuit with the similar primary connections 28 and 29 so as to operate the transformers whenever this operating switch is closed. It is also desirable to have in connection with this operating switch a suitable starting switch or start ingcontacts so as to produce in the working circuit suitable high potential starting impulses when the operating switch is closed. This may be secured by providing the starting contacts 135, 138 in connection with the operating switch itself so that when this switch is closed the starting contacts are electrically connected and the starting circuit therethrough is closed so as to allow current from the starting battery 48 to pass through the wire 38 and the contact 45, of the magnetic break 143 which is normally closed by the light spring indicated and which may be provided with a suitable starting armature 14:2 cooperating with the magnetic core 144 of the starting and-equalizing coil 43. This starting circuit may also comprise a suitable starting primary 44 co operating with this magnetic core 14A and connected by the wire 35 with the starting contact 135.

this starting The current passing through circuit when the operating switch is first closed energizes the core 144 and this acts sufficiently 0n the starting armature 142 to cause the magnetic break to interrupt this starting circuit and send an intermittent high potential impulse through the working circuit, the connections being of course preferably so arranged that this starting impulse acts in the same direction as the normal working current. If this starting impulse or spark is insufficient to break down the starting resistance of the tube or other device and initiate the passage of the normal working current the light spring again closes the magnetic break and a series of such starting impulses continues to be produced by the coil until the normal working current regularly passes through the working circuit and X-ray tube, for ex-' ample, a suitable sparking condenser 47 being if desired connected by the wires 46, 146 around the magnetic break as indicated to minimize sparking at that .point. Thereupon the working current passing through the starting and equalizing coil 43 sufficiently energizes its core to act on the starting armature and keep open the starting circuit so as to prevent any further irregular starting impulses and to allow the substantially uninterrupted uniform working cur-- rent to act alone in the tube or other translating device.

The Villard type tubes are especially desirable for use in rectifying such high potential currents as are desirable for X-ray work and the like which are of relatively small amperage, say, from a few m illi-- amperes to two or three hundred milliamperes or so in ordinary work. These tubes, especially when used at relatively low vacuum give good reliable results and are quite uniform in their action and are especially desirable because they are always ready to operate without requiring any special starting devices. It is, however, preferable to use a series of such tubes in every instance to promote their uniformity of action and also to secure proper rectification of such high potential currents when the tubes are used at the relatively low vacuum which seems desirable. A series of such tubes may be conveniently mounted to form a valve tube rectifying unit by the use of the valve tube rack shown in Figs. 3 and- 4. The rack rods 50, 51 which may be made of suitable insulating -material, such as varnished wood, vulcanite or the like, may be connected by the suitable metallic end connectors or brackets 49 so as to be rigidly held in position. A number of suitable flexible tube clamps 52, which may be formed of sole leather or other suitable material may be strung upon these rack rods and be formed with suitable gripping rods and with a central clamping aperture lating form of valve holes to quite closely engage the to cooperate with the tube ends .60, as shown in Fig. 4. By forcing these tube clamps into the curved positions indicated in Fig. 3,their ends assume a sufficiently diagonal position with respect to the rack rods to securely clamp them thereto firmly in position, but without undesirable rigidity which might promote breakage. A suitable wire or the like 97 may connect the anode of the lower valve tube 53 with the bracket or end connector 49 at the lower end of the rack and the intermediatewires or connectors 99 may similarly connect the intermediate valve tubes, anode to cathode so as to form a series arrangement, the upper wire 98 connecting the cathode of the upper tube to the end connector or bracket 49 'at the top of the tube rack, thus making an interchangeable valve tube rack or unit which may be readily replaced in connecting the transformer secondaries with the working circuit.

It is highly desirable to have a self-regutube for this work and the form of tube shown in Fig. 5 is desirable in this connection. The exhausted glass body is'form'ed with the projecting end 59 through which extends the terminal of the cathode which may as indicated be in the form of a spiral 55 of aluminum wire or other material and the effective area of this negative electrode when the rectified current is passing through the tube may, if. desired be increased by inserting therein cylindrical sheet metal electrode 56 which may be forced into connection with. the spiral wire, or if desired be suitably connected to the terminal in any other way and act alone as the cathode. The anode 58- is of relatively small area and its effective area is still further reduced by being surrounded and hold the valve tubes a suitable or loosely embraced by the small glass tube located within the exhausted tube body 5 3,

so that there may be arranged thereon or in. connection therewith suitable salts 57, such as fused potassium or sodium hydrate capable of developing sufficient gas to reduce the vacuum when. this restricted passa e 157 becomes heated on theundesirable D a increase of the tube vacuum. It is of course understood that these Villard type valve tubes are so proportioned that the effective anode surface is made so small in connection with the reduced chamber in which the anode is located as to have the proper valve or rectifying action in connection with the large containing chamber andv efiective surface of the cathode. Another formof regu lating valve tube which may be used in this sion 69 of the tube.

reduce the vacuum and again disperse the.

be given the form of a concave cup 62 which may have a central hole 63 and be supported by the stem 54 mounted in a lateral exten- Under normal conditions of desirable low vacuum the cathode stream is dispersed and the tube has the normal valve action; WVhen, however, the tube vacuum becomes undesirably high the cathode stream is concentrated so as to strike the salt 57 mounted upon a suitable support 177 so as to evolve suflicient gas to cathode stream and stop the evolution of gas. The support 177 may be made adjustable within the tube by being mounted on a threaded stem 64 which may cooperate with a suitable nut 164 mounted in the tubular glass support 159 in the reduced end 59 of the tube. By securing a suitable operating weight 61 on the stem 64 the rotation of the threaded stem and consequent screw adjustment of the support 177 may be secured by holding the tube with its axis substantially horizontal and rotating it to the desired extent. Still another torm of self-regulating valve tube is indicated in Fig. 7 in which the enlarged cathode 71 may be given the concave form indicated and be mounted on the metallic stem 73 in the extension 59 of the tube. The'anode 58 is mounted in the usual way in the other end of the tube beyond the restricted passage or neck 157 of the anode chamber 60 and may have electrically connected therewith by the wire 72 or otherwise a suitable electrode 66 arranged in a suitable depression in the tube and surrounded with a mass of high insulation 65. When the vacuum in the tube becomes undesirably high the potential difierence between the cathode and the anode is correspondingly increased and this increases the electrical attraction between the cathode stream 68 and the electrode 66 so as to attract the cathode streamtoward the electrode and cause its impingement upon the gas producing salt 57 on a suitable support 67 mounted in the tube. W'hen, however, the vacuum is sufficiently reduced to restore normal conditions, the cathode stream no longer impinges sufiiciently on the support to cause further action on the salt carried thereby.

While of course any suitable form of X-ray tube may be used in connection with this apparatus, a desirable tube is indicated in Fig. 1 in which the cathode '75 may be formed of thin aluminum or other material substantially transparent to X-rays while impervious to the undesirable radiation. This cathode may be supported in tension indicated as connected to the corrugated body 42. of the tube. This tube is adapted to work at high efficiency and to give good radiographic effects while developing a minimum amount of undesirable radiation. This tube 42 may be connected to the working circuit as indicated in Fig. 1 and it is desirable in order to secure best results to have a suitable milli-ammeter such as 3 located in this working circuit. For many purposes it is also desirable to have a suitable luminous oscilloscope such as 1 in the working circuit and for radiographic work it is advantageous to have such an oscilloscope mounted adjacent the ammeter so as to illuminate its dial when the tube is being operated. This may be effected by mounting the oscilloscope close to and preferably slightly above the dial of the milli-ammeter which may be done by connecting it in series therewith and with the tube by the wires 4 and 41 so that the luminosity of the electrodes 2 will give some indication of the current passing and also enable an accurate reading to be made of the adjacent milli-ammeter needle when desired.

Having described this invention in connection with a number of illustrative embodiments, forms, proportions, arrangements and. connections of parts, to the details of which disclosure the invention is not of course to be limited, what is claimed as new and what is desired to be secured by Letters Patent is set forth in the appended claims.

1. In X-ray apparatus, three-phase transformers, an operating switch to simultaneously connect the primaries of said transformers to a three-phase supply circuit, a

working circuit comprising an X-ray tube,

a series of Villard type valve tubes connecting each of said transformer secondaries to each side of said working circuit to deliver superimposed rectified impulses thereto, said Working circuit-comprising a starting and equalizing coil tending to equalize the normal working current passing therethrough, a magnetic core cooperating with said equalizing coil; a starting circuit comprising a starting primary cooperating with said core to energize the same, a source of potential, a magnetic break operated by said core in series with said starting primary and contacts connected to said operating switch to send intermittent high potential impulses through said working circuit until the normal working current passes therethrough and holds open said magnetic break.

2. In X-ray apparatus,'three-phase transformers, an operating switch to simultaneously connect the primaries of said transformers to a three-phase supply circuit, a

working circuit comprising a high potential vacuum tube, a series of vacuum valve tubesconnecting each of said transformer secondaries to each side "of said Working circuit to deliver superimposed rectified im-,

pulses thereto, said working, circuit comprising a starting and equalizing coil tending to equalize the normal working current passingtherethrougli, fa magnetic core cooperating with said equalizing ,co'il; a start- 1 ing circuit comprising a starting primary coiiperating with said core to energizethe same, a source of potential," a magnetic break'operated by said core inseries with said starting: primary" and contacts con;

" ei ected-jto said,operatingswitch to send iii-g termittent high potential impuises througlr said working circuit until the normal worktherethrough and "holdsing current passes open said magnetic break; an ammeter in said working circuit and a luminous oscil loscope n said working circuit and coopcrating with saidammeter to illuminate the formers, a working working circuit I vregulating valve" tubes i X -ray.tube,' one or tubes. connecting each of said transformer isecondariesto each 'si d'e of said workingfl same.

X-ray tube, a series circuit to deliver superimposedrectified impulses thereto, said Working circuit comprisingan equalizing coil tending to equalize the-j normal working current passing therethrough and a magnetic core cooperi ating with said equalizing'coil;

'5. In X-ray apparatus, polyphase trans formers, an operating switch to simultaneously connect the primaries of said transformers to a polyphase supply circuit, a workworkin -izing coil a starting ing circuit comprising an- X-ray tube, a series of Villard type valve tubes connecting each of said transformer secondaries to each side of said working circuit to deliver superimposed rectified impulses thereto, said equalizing coil tending to equalize the normal working current passing therethrougli, a magnetic core cooperating with said equalcircuit comprising a starting. primary cooperating with said core to energize the same, a source of poten tial, a magnetic break operated by said core in series with said starting primary circuit comprising a starting andand contacts connected to said operating switch to send intermittent high potential impulses through said working circuit until the normal working current passes therethrough and holds open said magnetic break; an ammeter in saidworking circuit and a luminous oscilloscope in said working c-ircuit and cooperating with said ammeter to illuminate the same.

161111 X-ray apparatus, polyphase trans- -forniers, a high potential working circuit comprising a high potential vacuum tube, one or more self-regulating valve tubes connecting each of said transformer secondaries to each side of said working circuit to deliver,v superimposed rectified impulses thereto, said working circuit comprising a starting and equalizing coil tending to equalize the normal working current passing theretlirough, a magnetic core cooperating with said equalizing coil, a starting circuit comprising a starting primary cooperating with said core and adapted to be connected to a source of potential to energize said core and a magnetic break operated by said core in series with said starting primary to send intermittent high potential impulses through said working circuit until the normal Working current passes therethrough.

' 7., In X-ray apparatus, polyphase transformers, an operating switch to simultaneously connect the primaries of said transformers to a polyphase supply circuit, a working circuit comprising an X-ray tube, a series of Villard type valve tubes connecting each of said transformer secondaries to each side of said working circuit to deliver superimposed rectified impulses thereto, said working circuit comprising a starting and equalizing coil tend ng to equalize the normal working current passing therethrougli, a starting circuit comprising a starting primary cooperating with said coil to energize the same, a source of potential, a magnetic break operated by said coil in series with said starting primary and contacts connected to said operating switch to send intermittent high potent'ial impulses through said working circuit until the normal working current passes therethrough.

8. In X-ray apparatus, polyphase transformers, an operating switch to simultaneously connect the primaries of said transformers to a polyphase supply circuit, a

working'circuit comprising. an X-ray tube, a rectifying device connecting each of said transformer secondaries to each side of said working circuit to deliver superimposed rectified impulses thereto, said working circuit comprising a starting and equalizing .coil tending to equalize the normal workpassing tlieretlirough; a starting current comprising a starting primary ing circuit coiiperating with said coil to energize the same; a source of potential. a magnetic break operated by said coil in series with said starting primary and contacts connected to said operating switch to send intermittent high potential impulses through saidworking circuit until the normal working current passes therethrough.

9. In X-ray apparatus, polyphase transformers, a working circuit comprising a high potential tube, a rectifying device connecting each of said transformer secondaries to said working circuit to deliver superimposed rectified impulses thereto, said working circuit comprising a starting and equalizing coil tending to equalize the normal working current passing therethrough, a magnetic core cooperating with said equalizing coil, a starting circu t comprisinga starting primary cooperating with said core and adapted to be connected to a source of potential to energize said core and a magnetic break operated by said core and m series with said starting primarv to send in termitt'ent high potential impulses through said working circuit until the normal working current passes therethrough.

10. In X-ray apparatus, polyphase transformers, a workin circuit compr singan X-ray tube, a rect fying device connecting each of said transformer secondaries to said working circuit to deliver superimposed rectified impulses thereto, said Working circuit comprising a starting and equal zing device tending to equalize the normal working current passing therethrough and a starting circuit cooperating with said starting device to send an increased potential impulse therethrough and promote the passage of the normal working current.

11. In X-ray apparatus, polyphase transformers, a working circuit comprising an X-ray tube; a rectifying device connecting each of said transformer secondaries to said working circuit to deliver superimposed rectified impulses thereto, said working circuit comprising a starting and equilizing device tending to equalize the normal working current passing therethrough and an operating switch operating said transformersand sending a starting current through said starting device to send a high potential impulse through said working circuit promoting the passage of the working current therethrough.

12. In X-ray apparatus, polyphase transformers, a working circuit comprising an X-ray tube, a rectifying devi'cer 'connecting each of said transformer secondaries to said working circuit to deliver superimposed rectifying impulses theretojof a potential suitable for X-ray tube work, said working c1rcuit comprising an equalizing device" tending to equalize the normal working current passing therethrough. I

13. In X-ray apparatus, polyphase high potential-supply circuits, a Working circuit coil tending to equalize the normal comprising an X-ray tube, a high potential vacuum tube rectifying device connecting each of said supply circuits to said working a secondaries to each side of said working circuit to deliver superimposed rectified iinef pulses thereto, said working circuit compris- 7 ing an equalizing coil tending to equalize the normal working current passing therethrough.

15. In X-ray apparatus, polyphase transformers, a Working circuit comprising an Xray tube and one or more Villard type valve tubes connecting each of said transformer secondaries to each side of said working circuit to deliver superimposed rectified impulses thereto.

'16. In high potential vacuum apparatus, polyphase transformers, 'a working circuit comprising a hi h potential vacuum tube, one or more VilIard type valve tubes connecting each of said transformer secondaries to each side of said working circuit to deliver superimposed rectified impulses thereto, said working circuit comprising an equilizing working current passing therethrough.

17. In high potential vacuum apparatus,

polyphase transformers, an operating switch to simultaneously connect the primariescf v saidtransformers to a, polyphase suppl cuit, a'working circuit comprisin a big .vpo;

tential vacuum tube, a series of illard type valve tubes connecting each of said trans former secondaries to each'side of said working circuit to deliver superimposed rectified impulses thereto, said working circuit comprising a starting and equalizing coil tend- -;ing to equalize the normal working current passing therethrough; a starting circuit comprising a starting primarycooperating with said coil to energize the same, a source of potential, a magnetic break operated by said coil series with said starting primary and contacts connected to said operating switch to send intermittent 'high potential impulses through said working circuit until the normal working current'passes therethrough.

18. In high potential vacuum apparatus,

polyphase transformers, an operating switch :QtiaI, a magnetic aries' to each side of said working circuit to deliver superim osed rectifi'd impulses thereto, said wor 'ng circuit comprising a starting and equalizingcoil tending to equal- 2 ize the normal wor 'ing current gassing- I;

therethrough .a starting circuit comprising i a starting primary cooperating with said the same, aisource of otenh break operatedby said. can in-series with said starting primary and con- 7 coil to energize v tacts connected to saidoperating switch to ma! working current v iiiin highr'potential 'vaeumn apparatns,,

sendint'ermittent high; potential impulses through said working 'circni't' until 'thenorpassesj-therethrough.

pol-y a .worlnngbcircuita operating wi-tl' i 'saidstartin an increased potential iin'pu se therethrough and promote the passage "of the normal working current; I EUGENE CALDWELL. Witnesses: I p Y I HARBI= L."DUFCAN,-

Jnssm'B. KAY. 

